1. Field of the Invention
This invention relates to a driving device for loading/unloading a tray in a tray type cassette loading apparatus of a digital audio tape player which is the subject matter of U.S. Pat. application Ser. No. 07/455,178 filed Dec. 22, 1989 now U.S. Pat. No. 5,062,015.
2. Description of the Prior Art
FIG. 1 of the accompanying drawings illustrates in a perspective view a tray type cassette loading apparatus as disclosed in a prior application in the name of the applicant of this application, which apparatus comprises a cassette holder(1); an up-and-down plate(3) mounted on the cassette holder (1) to be rotatable by means of a shaft (2); a tray(4) connected to the cassette holder (1) and the up-and-down plate(3) to be movable horizontally; opposite brackets (5) fixedly disposed in parallel on opposite sides of a main base to support the cassette holder (1), the up-and-down plate(3) and the tray(4); a cam gear (7) comprising an integrally formed inner intermittent gear (7a) (depicted by the chain line) meshed with a rack of the tray (4), an outer gear (7b) formed on its entire circumference to be meshed with a transmission gear(8), and a cam groove (7c) formed in its inner surface, and mounted on one of the brackets(5) to be rotatable by means of a rotary shaft(9); and up-and-down holder (11) pivotally coupled to rear ends of the opposite brackets (5) through a shaft (10) to rotate the up-and-down plate (3); a cam lever(13) connected at its rear end to the shaft (10) and having at its forward end a pin (12) received in the cam groove (7c), and thus pivoting the up-and-down holder (11); an adjusting piece (14) having a projection (14a) and disposed in contact with a bent portion (11a) of the up-and-down holder(11); and a spring(15) connected at opposite ends to the up-and-down holder(11) and the cam lever (13) to extent between them.
The cam groove(7c) of the cam gear (7) is comprised of a snail-shaped groove having a first section for a horizontal movement of a cassette, a second section for a vertical movement of the cassette, a third section for keeping a substantially constant distance between the pin(12) of the cam lever(13) and the bent portion(11a) of the up-and-down holder(11) and allowing the cassette to have an extra stroke by applying upon the cassette pressure proportional to tensile force of the spring (15) by means of a further rotational movement of the cam lever(13), and a fourth section for preventing the cam gear (7) from reversely rotating by means of restoring force of the spring (15). With this construction, tape loading/unloading operation may be carried out with the horizontal and vertical movements of a tape (not shown) loaded into the cassette holder (1), in accordance with the complex movements of the parts as described above. For further details of the operation of the loading apparatus, because reference may be made to the above-mentioned prior application of this applicant, the description is omitted herein to avoid duplication.
In order to load/unload the tape by horizontally and vertically moving the cassette holder (1) of the tray (4), the cam gear (7) rotatively driven by means of the rotary shaft (9) horizontally moves the tray (4) through the rack (6) of the tray, which is meshed with the inner intermittent gear (7a) provided on the inner side of the cam gear, and vertically moves the tray through the pin (12) of the cam lever (13), which moves along the cam groove (7c) formed in the inner side of the cam gear. In this manner, in order to rotate the cam gear (7) for moving the cassette, there are needed a drive unit is required for transmitting power to the cam gear, and a suitable control means for the drive unit.